PSI - Issue 2_B

Daniel F. C. Peixoto et al. / Procedia Structural Integrity 2 (2016) 1904–1911 Author name / Structural Integrity Procedia 00 (2016) 000–000

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Figure 12: K V max vs. crack length.

Concluding remarks The commercial finite element package ABAQUS 6.12-3 was used to build and analyze a 2D model of a subsurface crack propagation on the wheel/rail contact. The Maximum Tangential Stress (MTS) criterion was used to calculate the mode I and II stress intensity factors and the crack propagation direction along the crack tips loading cycle. Particular attention was dedicated to the propagation direction of the crack at every increment of its length. As can be observed in the presented results the crack change its direction from approximately +60º to -60º at every increment of the crack length. This will promote a very irregular crack surface until the final fracture occurs. As rolling contact induces complex non-proportional mixed-mode conditions at crack tips, the evolution of mode I and mode II stress intensity factors was followed along the loading cycle and no dominant mode at the crack tip was observed despite of the equivalent stress intensity factor being very sensitive to the variation of the mode II stress intensity factor. In this study the calculation process ended when the maximum mixed mode equivalent stress intensity factor reached a value considered in the unstable propagation zone, which implies that the crack will growth rapidly until reaches the wheel surface. Acknowledgements Daniel Peixoto acknowledges a Calouste Gulbenkian Foundation PhD grant, number 104047-B. The Portuguese Science and Technology Foundation FCT project PTDC/EME-PME/100204/2008 “Railways” is acknowledged. ALSTOM kindly supplied the Spanish AVE high speed train wheel for this study. References ABAQUS, ABAQUS v6.12-3 documentation, Dassault Systèmes. Dubourg, M., Lamacg, V., 2002. A predictive rolling contact fatigue crack growth model: onset of branching, direction, and growth-role of dry and lubricated conditions on crack patterns. Journal of Tribology 124(4), 680–688. Erdogan, F., Sih, G., 1963. On the crack extension in plates under plane loading and transverse shear. Journal of Basic Engineering, 85, 519–525. Henn, K., Richard, H., Linnig, W., 1988. Fatigue crack growth under mixed mode and mode ii cyclic loading, in: Czoboly E., Fracture analysis - theory and practice, EMAS Ltd, Warley, 2, pp. 1104 – 1113. Peixoto, D.F.C., de Castro, P.M.S.T., 2016. Mixed mode fatigue crack propagation in a railway wheel steel’ Procedia Structural Integrity 1, 150 157. Qian, J., Fatemi, A., 1996. Mixed mode fatigue crack growth: a literature survey,’ Engineering Fracture Mechanics, 55(6) 969–990. Richard, H., Linnig, W., Henn, K., 1991. Fatigue crack propagation under combined loading, Forensic Engineering, 3, 99–109.